Solubility and dissolution thermodynamics of N-(4-chlorophenyl)-2-(pyridin-4-ylcarbonyl)hydrazinecarbothioamide in PG + water co-solvent mixtures at (298.15 to 338.15) K

• Solubility of isoniazid analog in various PG + water mixtures was measured.
• The solubility was observed highest in pure PG.
• Experimental solubilities were correlated well with Apelblat and Yalkowsky model.
• Solubilities were increased with increase in temperature and mass fraction of PG.

The objective of present investigation was to measure the solubility and dissolution thermodynamics of N-(4-chlorophenyl)-2-(pyridin-4-ylcarbonyl)hydrazinecarbothioamide [isoniazid (INH) analog] in various propylene glycol (PG) + water co-solvent mixtures from (298.15 to 338.15) K. The experimental solubilities of INH analog were correlated with Apelblat and Yalkowsky models. The root mean square deviations were found to be (1.13–3.98)% and (1.45–5.73)% for Apelblat equation and Yalkowsky model, respectively. Good correlation was observed between experimental and calculated solubilities of INH analog with correlation coefficients in the range of 0.995–0.999. The mole fraction solubility of INH analog was found to be highest and lowest in pure PG (7.38 × 10−3 at 298.15 K) and pure water (5.17 × 10−7 at 298.15 K), respectively. The results of dissolution thermodynamics indicated endothermic and non-spontaneous dissolution of INH analog.